Question Bank [2022] — BIOLOGY STD 12 Science — Question

A moss plant produces a large number of antherozoids but relatively only a few egg cells. Why?
OR
Why do moss plants produce very large number of male gametes? Provide one reason. What are these gametes called?

On which observation, the law of segregation is based?

Is the use of contraceptives justified? Give reasons.

Consuming curd keeps the gastrointestinal tract intact. Give reason.

Differentiate between the roles of B-lymphocytes and T-lymphocytes in generating immune response.

What are we referring to when we say 'simple organisms' or 'complex organisms'?

Give an example of a plant which came into India as a contaminant and is a cause of pollen allergy.

What is hybrid sterility?

Answer the following:

1. Highlight the role of thymus as a lymphoid organ.
2. Give the name of the cells that are released from the above mentioned gland. Mention how they help in immunity?

Name any two organisms and the phenomenon involved where the female gamete undergoes development to form new organisms without fertilisation.